README 增加界面预览截图

- docs/frontend.png:公开看板 demo(?demo 模式,浅色主题,1920×1000)
- 补提交已放置的 docs/backend.png(管理后台),README 中两图配套展示

README.md

@@ -4,6 +4,7 @@ NodeFlare 是一款轻量级、可自托管的服务器监控面板：通过 Web
 
 English: [docs/README.en.md](docs/README.en.md)
 
+- [界面预览](#界面预览)
 - [特性](#特性)
 - [平台支持](#平台支持)
 - [安装服务端](#安装服务端)
@@ -16,6 +17,12 @@ English: [docs/README.en.md](docs/README.en.md)
 - [开发](#开发)
 - [排障](#排障)
 
+## 界面预览
+
+![公开看板](docs/frontend.png)
+
+![管理后台](docs/backend.png)
+
 ## 特性
 
 **监控与展示**

docs/README.en.md

@@ -4,6 +4,7 @@ NodeFlare is a lightweight, self-hosted server monitoring panel: view server sta
 
 Chinese: [README.md](../README.md)
 
+- [Screenshots](#screenshots)
 - [Features](#features)
 - [Supported platforms](#supported-platforms)
 - [Install the server](#install-the-server)
@@ -16,6 +17,12 @@ Chinese: [README.md](../README.md)
 - [Development](#development)
 - [Troubleshooting](#troubleshooting)
 
+## Screenshots
+
+![Public dashboard](frontend.png)
+
+![Admin panel](backend.png)
+
 ## Features
 
 **Monitoring**